This invention relates to sanitizing food products, which preserves their appearance and extends their shelf life.
As one technique for sanitizing a food product, it is desirable to eliminate microbial contamination from the surface of the food product before the food product is presented to the consumer for consumption.
Conventionally, food products have been sanitized by immersing the food product in a water bath or in a flowing stream of water containing such sanitizing agent, following which the food product is centrifuged to remove water. This is a relatively unsatisfactory technique because the product retains so much water that retaining the physical properties, freshness and attractive appearance of the original product becomes difficult.
It has also been proposed in the past to employ ozone, or aqueous solutions containing ozone, to clean food products. The prior art disclosures concerning this proposal are also lacking in understanding of how to achieve superior shelf life extension. For instance, U.S. Pat. No. 5,858,435 discloses a method of cleaning produce that includes the steps of rotating the produce on a conveyor while spraying it with a mixture of water and ozone, and brushing the produce with a rotating brush head so as to dislodge dirt, mold and the like from the produce by the rotating brushes, followed by another step wherein a mixture of water and ozone is applied to the produce and the produce is then treated to remove excess water from the exterior thereof, and as a final step a food grade wax is applied to the produce. This technique is completely unsuitable for many types of food products. The physical action of the brushes can dislodge or tear the food product, rendering it less visually attractive to the consumer, while in addition the brushes can not only pick up the dirt that may have been present on the food product, but also pick up shreds of the food product itself. This necessitates periodic cleaning of the brush bed, so the brush bed must be considered to be a source of fresh contamination for the food product. This patent also fails to recognize the significance to shelf life of the presence of water on the food product and within interstices of the food product. Indeed, the requirement in this patent of applying a layer of wax onto the food product confirms a failure to appreciate the significance of maximizing removal of residual water from within interstices of the food product in order to obtain a desired increase in the shelf life of the food product.
Thus, there remains a need for methods for rapidly, efficiently and effectively sanitizing food products.
One aspect of the present invention is a method of sanitizing a food product, comprising.
applying an aqueous sanitizing liquid onto the food product by spraying it onto all exterior surfaces of the food product from a plurality of directions while moving the food product laterally with respect to the sprays, wherein the velocity of each spray is sufficient to wet microbes adhered to the surface of the food product,
wherein the sanitizing liquid comprises ozone at a concentration of up to 15 ppm, and preferably also comprises at least one agent which inactivates food microbes wherein said agent is present in a concentration sufficient to inactivate food microbes,
maintaining contact between said sanitizing liquid and said food product for at least a time effective to maximize wetting of the surface of the food product by the sanitizing liquid containing said at least one agent,
and then removing mechanically at least 75% of said liquid from said food product.
In a preferred embodiment, the removal of liquid is effected by positioning beneath the food product a device comprising
a main conduit oriented vertically and open at its upper and lower ends, and preferably having at its upper end an annular flange terminating in a planar top surface,
an air knife means sealingly connected to an opening in the side of said main conduit and positioned in said opening to eject air or other gas downward in said main conduit, wherein the inside diameter of the main conduit between said opening and said upper end is less than the inside diameter of the main conduit below said opening,
wherein the portion of the main conduit downstream of said opening, beginning from said opening, exhibits an expansion angle of up to 3 degrees and preferably greater than 0.5 degrees for a distance at least 6 times the diameter of the main conduit at said connection, and
gas supply means in fluid communication with the inlet of said air knife means for blowing gas into said inlet at a velocity sufficient that said gas is ejected into said main conduit at a sufficient velocity to draw air and any liquid entrained in the air into said upper end and out said lower end,
and actuating said gas supply means so as to draw liquid off of food product positioned over said device.
The method of this invention also prolongs the appearance of freshness of food products, especially vegetables and fruits. That is, the method of the present invention retards the loss of the fresh appearance of the food product.